1. Field of the Invention
The present invention relates to processes for the alkylation of aromatics and processes for the production of ethylbenzene, and particularly to a dual-zeolite catalyst for the production of ethylbenzene.
2. Description of the Related Art
Ethylbenzene is used in the production of styrene. For this reason, most ethylbenzene plants are located close to styrene plants. Commercially, two processes are used to produce ethylbenzene.
The first process involves reaction of ethylene with benzene in the presence of an aluminum trichloride catalyst and hydrochloric acid in a Friedel-Crafts reaction, which may be done either in the liquid or the vapor phase. Although widely used, the Friedel-Crafts process has some drawbacks. The process does not stop at mono-substitution, but also produces diethylbenzene and triethylbenzene. Further, the spent catalyst cannot be used again. The cost of disposing of the catalyst is high, and has associated environmental problems with wastewater due to the corrosive nature of the materials.
The second process is usually a two-step process involving the dehydrogenation of ethane using a first zeolite to produce ethylene, followed by reaction of the ethylene with benzene in the presence of a second zeolite. The zeolite catalysts are non-corrosive, reducing environmental and disposal problems, and the zeolites selectively produce ethylbenzene to the exclusion of polysubstituted benzene. However, the low yield from the process makes the process expensive.
Thus, a dual-zeolite catalyst for the production of ethylbenzene solving the aforementioned problems is desired.